The overall goal of this project is a super-high-resolution simultaneous single photon emission computed tomography (SPECT) and x-ray computed tomography (x-ray CT) system for molecular imaging in small animals. The reconstructed system spatial resolution will be 500-750 um for SPECT and 50-100 um for x-ray CT. The dual modality images will be acquired simultaneously on two separate detectors and automated software will register and fuse the SPECT and CT images so that the features are superimposed. The entire system will be compact enough to mount on a mobile cart so that procedures can be performed in different parts of the laboratory. In Phase I we will work with vendors to develop the scintillates and readout components for the SPECT system in order to achieve the desired spatial resolution. The resulting prototype SPECT camera will be used together with a phosphor coupled to CCD via tapered fiber optic x-ray detector system (to be provided by LORAD) to obtain the first simultaneous SPECT-CT data. The system performance will be evaluated and used as a basis for the Phase II system development. Some software will also be generated to fuse the SPECT and CT images. PROPOSED COMMERCIAL APPLICATION: The Phase I and II development will lead to a new generation of dual-modality imaging systems providing ultra high resolution information about both the anatomy and function of animal subjects under study. There are large emerging markets demanding advancement in techniques and capabilities for studying disease processes in small animals, including genetics research using transgenic and knock-out mouse models, cancer research for both diagnosis and treatment and drug development.